Lubricant and process of making same



Patented July 24, 1934 UNITED STATES PATENT OFFICE William B. D.Penniman, Baltimore, Md.

No Drawing. Application August 15, 1928, Serial No. 299,883

6 Claims. (01. 81-9) This invention relates to lubricants and to methodsof making the same.

The lubrication of bearings, gears, cylinders, and other parts ofmachines is dependent in a broad and general sense upon the mechanicalconstruction and speed and load on the bearing surfaces to belubricated, on the supply of lubricant, and on the kind and propertiesof the lubricant. In prior applications Serial Number 10 209,256 filedJuly 9, 1927 and Serial Number 256,308 filed February 3, 1928, of whichapplications, the present one is a continuation in part, certainprinciples of lubrication and lubricants have been set forth, andmechanisms, processes and lubricants disclosed for securing novelresults in the lubrication of machines, particularly for street railwaycars which illustrate the application of these discoveries andinventions. These inventions and discoveries are of broad application"and extend to any case where one solid material is caused to pass overanother, and where it is desirable to reduce friction to a minimum. Theconditions under which these two surfaces pass over one another varyfrom the high speed and high temperatures of the pistons of an internalcombustion engine to the swivel plates of a railroad turn table. Asindicated in the prior applications, the lubrication of a bearing, totake a typical case, is dependent upon first, the supply of lubricant;second, the viscosity of the lubricant; and third, the oiliness of thelubricant. The present invention is more directly concerned with thenature and properties of the lubricant and the methods of obtainingdesired lubricants having the most desirable properties as to viscosityand oiliness and other features as will more fully appear below.

Petroleum oil and oils of related nature such as those obtained fromshale and coal by distillation are the main supply of lubricants theworld over. These oils vary a good deal among themselves but in generalas the viscosity of the oil increases, the oiliness also increases.Consequently it has become the practice to specify the lubricant in 453terms of its viscosity thereby more or less loosely fixing the oilinessproperty desired. But in using these mineral and related oils bythemselves, it is necessary to use oils of relatively high viscosity, inorder to obtain the required degree of oiliness.

The use of heavy or viscous lubricating oils is well illustrated in thespecifications set out in Technical Paper No. 323A issued by the Bureauof Mines and entitled United States Government specification forlubricants and liquid fuels and methods of testing. On page 28 of thispaper, the names and grades of the various lubricants are given. In thispaper, the lightest grade of oil suggested for lubrication is calledClass A extra light, having viscosity of 135 seconds at 100 F. On page 9of this paper the whole Class A embracing oils with viscosities of from135 to 360 seconds is given as used for very light machinery. The use ofan oil of viscosity below 135 seconds at 100 F. is not contemplated.

This reference to the paper of the Bureau of Mines is sufiicient to showwhat the attitude of the entire industry is and the use of relativelyheavy lubricants is universally followed. Oils with a viscosity below135 seconds at 100 F. are known as the so-called spindle oils, but theserelatively light oils do not enter into the ordinary lubricationprogram.

It is customary, for example, in oils for use in the lubrication ofautomobile engines, where the speed and load are high, to mix with thelighter oil, large percentages of cylinder stock or other very heavyoils in order to obtain the desired adhesiveness; so much is this thecustom that petroleum lubricating oils are generally sold on the basisof their viscosity only, it being well known that the adhesiveness is inthis way secured to a greater or lesser extent.

\ This prior art practice is further illustrated by the practice inconnection with lubrication 0589 street railway journals or axles, whereoils of the viscosity of from 250 to 600 Saybolt have been used prior tothe present invention. Further in this as in analogous cases where theoperating temperatures of the hearing or related mechanism might beabout 100 F. or even higher, the viscosity of the lubricant was chosenwith this temperature in mind. The variation in viscosity with change intemperature over the usual operating range was quite marked in theseprior art lubricants so that when the lubricant operated at the highertemperatures, it had to be that more viscous at the lower temperatures.In fact in many instances, these lubricants in order togive therequisite viscosity at the higher temperatures were actually solid attemperatures such as those frequently reached in this climate during thewinter season.

But the choice of heavy or viscous materials in order to secure adequateadhesiveness, results in a tremendous loss of power .due to the internalfriction of the lubricant, and these losses in power were either notrecognized or not appreciated in the prior art.

One of the objects of the present invention is the use of lubricants ofthe lowest possible vis- 110 But in any event, in accordance with thepresent invention, the oil of lowest lower the viscosity, lubrication.

But while the viscosity should be as low as possible, the adhesiveproperties should be as high surfaces of the service.

It has been known for some years that the property of oiliness of theordinary petroleum oil is improved by the addition of saponifiable oilor fatty acids of saponifiable oil.

' The principle on w ch an oily or greasy agent is added to thepetroleum or other stock is based upon the fact that bearing surfaces bytheir surface energy preferentially attract from the lubricant tothemselves certain portions of the lubricant, and it has been shown thatthe first layer of molecules so attracted may be held to the hearingsurfaces with great tenacity. This initial layer upon the surfaces isalmost infinitely thin, and though useful, is not sufliciently thick toproother surfaces when as a general rule.

These adsorbed substances may be termed "polar bodies since there isvention are accordingly the use of low viscosity lubricating oils with Afurther object of this invention therefore is the production oflubricants, particularly of low viscosity, that have the property ofbuilding up these mush" layers and thus eifectiveness of the initial orprimary adherent layer.

as mineral oils also oxidize to a the vegetable and animal oils.

Other objects and advantages of this invention will appear from the moredetailed description set forth below, it being understood however thatinvention as herein disclosed.

And as set forth above, the most desirable form of the lubricant will bea compounded oil that possesses low viscosit high adhesiveness, the

and that is not-changed by oxidation to any extent that renders itundesirable for lubrication.

The present invention is therefore broadly concerned with the use oflubricating oil stock whethmaterial tion 'of the The low viscosity stockmay be used ior lubri-' cation by itself in those cases where it ispumped about a hearing,

by external means, as in the case of turbines; but its use in theordinary bearing where no pumping action is present aside from thatproduced by the rotation of the hearing it-. self or the journal, ispreferable in conjunction with the added ingredients for improving itsproperties as to oiliness and mushiness. It is a significant fact thatsuch low viscosity material could not be secured on the open market thevarious oil companies and refineries developed. So that such lowviscosity material had to be made for the first time and methods weredeveloped for its production.

For example, a desirable stock may be made as by distilling off about I5percent of the lighter from kerosene oil and using the remainder in thestill-as stoc for the preparafinished lubricant. There results a productof requisite flrepoint and cold test with much lower viscosity than- 7available today, and these products may in general be said to have aviscosity of less than 150 seconds atl00 F. A speciflc' product obtainedby' distilling off '15 percent of ordinary coal oil tested as follows:

Specific gravity at 60 F l 383 B. Flash point 2405!. Fire p0int 2'15 I.Viscosity at F '14 sec. (8.1).) Viscosity at 60 F 56 sec. Viscosity at80 F sec. Viscosity at 100 F 40 sec. Viscosity at 210 F 31 sec. Coldtest Below 0 F. Total saponiflable matter 11.3% Free fatty acids 1.2%

' the present invention,

Similar products) as to viscosity may be prepared from any of the otherdistillates of like boiling point, petroleum, coal tar or shale oil.

In general it may be stated that the viscosity of a hydrocarbon stockshould not be so lowthat flash point of below about 225 these factorsare variable depending on the use to which thelubricant is-to be put.

. Such products as those 'indica d above are particularly desirably usedin connection with and in the case of the product I11 above, in view ofthe further fact those commercially that this material a substantiallyuniform viscosity over the usual workinz scale, it is all the moredesirable.

'1. cr'l'hompson in his-standard work on'this subject lists eighteenoils with viscosity numbers of from pm 18 and ranging inviscosity asfollows:

Sa boltseco ds va n cosity numbers 100" 1. 130 F. 212 F.

0 180 i 38 7 M0 115 43 s aw 100 so 9 500 230 55 10 65 ll 80 12 13 100 14130 15 165 16 190 17 700 18 Blown oils 1400 Of these, numbers 1-5 arethe so-called spindle oils, not generally considered in the lubricationprogram, butthey will be used in accordance with the present inventionwhen properly compounded for relatively heavy machinery; in addition tooils running from 65 seconds down as low as'can be obtained-probablyaround 35 seconds.

The proposed low viscosity material discussed above emphasizes the usein accordance with the present invention of material. Take for examplememe five oils of the Thompson tabulation. These oils if used in'theprior art are limited for lubrication purposes to use on textilespindles where the loadis almost zero and the speed is rather high.'They have not been used in lubricating heavy mathe lowest possibleviscosity chinery However when compounded in acfrom prior art andparticularly the higher fatty acids may be used. Further, the higher thefatt acid, the better its effect. Also, the presence of the hydroxylgroup in the molecule with the carboxyl group yields a better lubricant.As an example, attention may be called castor oil. But these bodieswhich may be referred to as indicated above as .polar bodies are notlimited to the fatty acids, and non-fatty acid polar bodies or compoundsor materials may be used. The higher alcohols and ketones areadvantageous and work almost as well as the fatty acids; sulphides andsome of the metallic salts are also eflicient though in general due tothe ready availability of the fatty acids and their cheapness, they aremore generally used.

In some cases, however, theme of fatty acids may be objectionable due tothe eiifect on the metal of the hearing or journal. Accordingly the'erations in mind.

to the may acids of The higher alcohols and ketones may be readilyobtained from the oxidation products obtained 'during the air blowing ofpetroleum and related materials particularly under pressure and atelevated temperatures, or from the residues remaining in' the stillduring such air blowing processes. The sulphides may be prepared bydirect treatment of petroleum oil with sulphur, the products beingsomewhat complex, but the polar bodies appear and their effect isavailable.

The mushfllayers may be obtainable with various substances. The besteffect is obtained with a material that is soluble in the polar body andquite, or totally insoluble in the petroleum oil, so that when a portionof the fatty acid or other polar body adheres to the metal surface toform the primary layer, a very considerable quantity of the mushsubstance will be withdrawn and a thicker and more coherent mush layerwill be brought up. Saponiflable oils or fats that contain some fattyacid to act as the polar body serve in this connection. If the amount offatty acid is small, the polar fatty acid will be withdrawn and will actto take up but a comparatively small quantity of the mush ingredient,namely the neutral glycerides or fats, and a comparatively thin and softcoating results. The presence of comparatively large quantities ofsubstances more attracted to the polar body will assist in building up abetter mush layer. A good example is castor oil dissolved in oleic acid,the castor oil being substantially insoluble in petroleum oil stockused. Two parts of castor oil to one part of oleic acid may be used. Theoleic acid acting as the polar body carries down with it largequantities of the castor .oil and the mush layer consists largely ofoleic acid and castor oil. This artificial or synthetic compositionbuilds up a better layer than does an ordinary animal oil consisting ofa mixture of some free chemical attraction orresidual chemical forces,

substances used in lubrication build up a surface film on the metallicsurface of considerable tenacity. Other substances may also form orbuild up such films but they are not of value as lubricants. In thosecases where the fatty acids are objectionable in a lubricant, thesubstituted ammonias that have little value as lubricants but build upfilms on the surface, can be used, if there is also added some materialof high lubrication power that is selectively adsorbed by thesubstituted ammonia or forms molecular aggregates with it. In thelubrication of internal combustion engines where high temperaturesprevail, the avoidance of such acidity is desirable. ,There may be usedin such cases a mixture of diphenylamine and tallow oil (.with little orno free acid). Good results are obtained when only 5 percent of thismixture is used.

Soaps which form an emulsion with the petroleum stock or which aresoluble in the petroleum stock can also be used. For example, soaps withpetroleum stock particularly the soda and lime soaps that are present ascolloids.

The soaps that go into solution include lead oleate, copper oleate, andthe oleates of the heavy metals generally, the alkalies and alkalineearth acid is preferable tolard oil, and castor oil when in solution asillustrated above is superior to either lard oil or tallow oil.

In some cases, the body added to improve the ,mushiness characteristicmay at'the same time possess a polar property so that in this way twopurpose, the following is given.

Sulphonic acids derived from the treatment of unsaturated petroleumcompounds, that is to say derivatives. mediates utilizable in thisconnection, mention or air upon the lubricant. be mentioned:

cent of the total admixture. When the oil is to be used at a relativelyelevated temperature,

one part of beta-betadinaphthylamine is added to the oil; while if theoil is to be used at norgood results in practice.

The amount of the anti-oxidant is varied according to the time at whichthe lubricant is to be used and the conditions as to oxidation. At

1 percent. The

very low temperature, the efiect of the oxygen is very little feared, sothat the amount of antioxidant used in such cases may be as low as .1 ofdinaphthylamine is desirable but tetra-ethyl lead has also proved to bemoderately eflicient.

While certain theoretical considerations have been given in theexplanation of the present invention, it should be noted that thetangible effects produced in accordance with the invention are notdependent on the theories stated, as the lubricants disclosed hereinhave been investigated under actual conditions of service and haveproved a tremendous advance in the art. Even when such terms as polarare used these terms need not be considered as implying a certain theoryof operation but may be taken as class or.

generic names.

As exemplary of the phenomenal results flowing from the presentinvention, attention maybe called to the fact that it has been appliedin the lubrication of a large railway system where about 30,000 bearingsare under study. Whereas, it had been the custom to use oils ofviscosity of about 250 seconds viscosity Saybolt prior to thisapplication of the present invention, following the principles set forthabove, the lubrication of bearings of the character of a street railwaycar is being made with oils of a viscosity of 35 seconds Sayboltuniversal viscosimeter, at 100 F. This lubrication with these oils oflow viscosity has alreadyresulted in the saving of approximately 15percent of the costs in operating these cars, though the entire systemis not yet fully equipped, and will result when full installation hasbeen made, in a saving or approximately 25 percent of the original powercosts, or a saving or hundreds of thousands of dollars annually.

Having thus set forth my invention, I claim:

1. A lubricating oil for heavy machinery containing a hydrocarbon oilhaving a viscosity considerably lower than that normally used for suchpurposes and within the range of 35 seconds to 65 seconds (Saybolt) at100 F., and from 2 to 10% of an organic component increasing theoiliness and adhesiveness of i the composition without substantialincrease oiwiscosity.

3. A lubricating oil for heavy machinery consisting of a hydrocarbon oilhaving a viscosity considerably lower than such purposes and within therange of 35 seconds to 65 seconds (Saybolt) at 100 F., and from 2 to 10%of a substance having high adhesive properties containing a largeproportion 01' saponiflable material which does not substantiallyincrease the viscosity of the composition.

4. A lubricating oil for heavy machinery containing a hydrocarbon oilhaving a viscosity considerably lower than that normally used for suchpurposes and within the range of-35 seconds to 135. seconds (Saybolt) at100 F., and from 2 to 10% of an organic component increasing theoiliness and adhesiveness of the composition without substantialincrease of viscosity.

5. A lubricating oil for heavy machinery conthat normally used fortaining a hydrocarbon oil having a viscosity considerably lower thanthat normally used for such purposes, and within the range 0! 35 secondsto 135 seconds (Saybolt) at 100 F., and from 2 to 10% of an organiccomponent containing a saponiflable glyceride, increasing the oilinessand adhesiveness of the composition, without substantial increase ofviscosity. I

6. A lubricating oil for heavy machinery containing a hydrocarbon oilhaving a viscosity considerably lower than that normally used for suchpurposes and. within the range of 35 seconds to 135 seconds (Saybolt) at100 F., and from 2 to 10% of an organic component containing asaponiflable glyceride oil and higher fatty acids increasing theoiliness and adhesiveness or the composition, without substantialincrease of viscosity.

WILLIAM B. D. PENNIMAN.

